Tunnel kiln



March 19, 1929. w..1 HANL-EY, JR 1,705,477

TUNNEL KILN Original Filed Aug. 30, 1926 5 Shets-Sheet 1 ATTORNEY March19, 1929. w. L. H ANLEY. JR I TUNNEL KILN o i al Filed Aug. 30, 1926 5Sheets-Sheet 2 Patented Mar. 19, 1929.

. WILLIAM LEE irANLnY, an, or BRADFORD, rnimsrnvaiim.

Application filed August 30, 1926, Serial No. 132,393. Renewed August 8,i928.

vMy invention consistsin the novel features tact with the hot firedproducts, after they hereinafter described, reference being had to leavethe firing zone, thus eifectingthe rethe accompanying drawings, whichilcoveryofa suitablc'amount of heat from thelustrate one embodiment ofthe same, a nd a fired products, the heating of the air so 60 slightmodification thereof, selected by me introduced and facilitating thecooling ;of for purposes of illustration, and the said -inthe firedproducts, and this highly heated vention is fully disclosed in thefollowing air from the cooling-zone is withdrawn theredescriptionandclaims. v v 7 from preferably at the end adjacent to the The object. ofmy invention is to produce firing zone where the temperature of thefired 5 10 a single tunnel kiln, especially adapted for products isgreatest, and isconducted preferthe firing of bricks and other coarseclay ably by means outside of the ki-ln, to the'preproducts. In theconstruction of such a kiln, heating zone, Where it is introduced and itis desirable to employ a simpleandeconombrought into contact with theunfire'd ware, ical construction inorder to minimizethe for the purposeof raising the temperature 15 very large initial cost of the kiln, andto keep thereof and supplying oxygen thereto,-?, to down the expensesofupkeep and repair. effect the preheating, water-smoking and Incarrying my present invention: into effect, oxidization of the Ware,before it reaches the I employ a single tunnel structure, which isfiring zone. I also prefer to providemeans entirely free fromlongitudinal fines or pasfor withdrawing the air, together with 2 sages,so that it can be very cheaply, convapors, gases, etc., produced inthese opera- I structed. The central portion of the tunnel tions, in thepreheating zone, so as to prekiln constitutes the firing zone, and isprovent the possibility of seumming or staining vided with furnacespreferably arranged in the brick during the preheating thereof.

a row along one side, or along both sides of I also prefer to providethe furnaces, or so 25 the firing zone which discharge theirprodburners, with regulating means, and to pronets of combustiondirectly into the firing Vide the passagesthrough which the productszone, so as to impart the greatest possible heat of combustion arewithdrawn from the firing to the goods and economy of fuel, theprodzone, and which are located preferably beucts of combustion beingwithdrawn from tween adjacent furnaces, with controlling the firing zonepreferably adjacent to eachor regulating means, so that the temperaturefurnace and conducted away from the kiln, of the firing zone may beregulated and; con-' the heat of such products of combustion b'etrolled.I preferably so regulate the teming recovered and utilized for dryingthe perature of the firing zone that at its enterproducts before firing,for heating air to be ing end it will maintain substantially thesupplied to the furnaces, or burners, and for temperature to which theunfired ware has w other purposes. This prevents the products beenpreheated, in passing through the pre- 1 of combustion from passing intothe other heating zone, the temperature of the firing portions ofthekiln, which comprise a prezone gradually increasing throughout theheating zone at one end of the firingzon'e, length thereof to thehottest portion, which 40 and a cooling zone at the otherend of the islocated'adjacent to the discharge end of heating zone, goodstransporting means'bethe firing zone, in accordance with what is ingprovided for conveying the goods termeda rising heat curve, which maybethrough the entire length of the kiln, s'ucof any desiredcharacteristic,according to cessively through the-preheating zone, firing theregulation of the individual regulating zone, and cooling zone, andcomprising prefdevices, before mentioned. invention crably, a pluralityof tu'nnel'cars extending provides an extermely' simple tunnel-kiln 1the entire length of the kiln, and running therefor, the initialccost ofwhich is small, upon suitable tracks. In order to raise the and which isentirely without internal incoming, unfired goods gradually to atemcomplications, contributing both to low ini-' .105 50 ieratureapproximatelythat ofthe entering tial cost and low cost of upkeepor-repair, and end of the firing zone, to preheat them, and greateconomy and efficiency of operation, is efi'ectthe water-smokingandoxidization of secured by advantageously utilizing practitheproducts, and at the same time utilize a ca-lly allofthe heat suppliedby the furnaces,

portion of the heat of the furnaces for this portions of which arerecovered from the purpose, provide means fordelivering air burned or.fired ware, andused in the pre: to the cooling zone Where 1t comes inconheating zone, and portions. of whlch are re.-

covered from the products of combustion and utilized for air heating anddrying purposes. 1

In the accompanying drawings, which illustrate one embodiment of myinvention, and a slight modification thereof, I

Fig. l is a diagrammatic, plan view of a single tunnel kiln embodying myinvention, and showing a drier for the uniired product-s arranged inconnection therewith and. heated from thewasteheat of the kiln furnaces,or

burners;

Fig. 2 is a horizontal, sectional view of a kiln drawn to an enlargedscale, and partly broken away. i

Fig. 3-is avertical section through the preheating zone of the kiln.

Fig. l is a transverse, vertical section through the firing zone of thekiln.

Fig; 5 is a horizontal plan view of a slightly modified form of singletunnel kiln, provided with a rowof furnaces at opposite sides of 7 1-1,extends longitudinally through the entire length of the kiln, and inoperation is occupied by a continuous lineof tunnel cars, 2, eachcarrying a carload of bricks, coarse clay or ceramic products to befired, indicated at 3, in dotted lines in Fig. 8. It will be understoodthat the kiln provides a longitudinal goods space, or passage, extendingfrom one end of the kiln" to the other, without either transverse orlongitudinal parvt-itions, and without any longitudinal flues.

. The end portions, 13, and C, ofthe tunnel, are

of very simple construction, and comprise the side walls, 4 4, and thecrown, 5, which may be of ordinary brick, or any other suitablematerial. The central portion, A, of the tunnel, which comprises thefiring zone, is also a single tunnel structure, which is'preferably madeof slightly greater width than the end portions of'the kiln, andcomprises the side walls, 4 and crown, 5 -5, the side walls being spacedfurther apart in order to accommodate a unitary bridge Wall, orwalls,'6,between the goods space and the furnaces, 'or'burners, whichare preferably arranged in a row on one side of the firing chamber, asshown in Figs. 1 to 4, or on both sides, as shown in Figs.'5 and 6. Inthe form shown in Figs. 1 to 4, where only one row of furnaces, 0rburners is employed, only one bridge or other wall is employed, arrangedon one side only of the goods space, indicated at D', in each of theseveral zones. The furnaces for firing the goods may be of any usualordesired ,characterand adapted for the consumption ,of any preferredfuel. In the present in stance I have shown the furnaces, 7, providedwith'a burner, 8, for a mixture of and air supplied by pipes, 9 and 10,respectively, under thecontrol of independent valves, 11 and 12,respectively, for each burner, so that each individual furnace may beindependently regulated, and a predetermined heat curve may bemaintained, increasing from thefentering end of the firing zone to thedischarging end thereof. For example, a temperature of 900 to 1400 F.,more or less, may be maintained at the entering end of the firing zone,the temperature of the different port-ions of the firing zoneincreasing, more or less gradually, to a temperature of 1800 to 2100 F.,more or less, at the discharge end adjacent to the cooling zone, C.W'here'other forms of furnac es are employed, the means forindependentlyregulating each furnace will vary with the character of fuelemployed. The products of combustion discharged from the furnace, orburners, are conducted upward through passages, indicated at 13, betweenthe side wall of the kiln'and the adjacent bridge wall, 6, and the upperends. of the bridge walls are pre'ferably'provided. with inwardlyextending portions at the top, as indicated at 6*, and if desired, alsoat one or more points below the top of the bridge wall, as indicated at6 in order to discharge the hot products of combustion into the upperpart of the goods space within the firing zone, and cause them todescend through the goods on the cars instead of between-the goods andthe bridge wall, as far aspossible. The bridge wall, 6, is connectedwith the adjacentwall, 4 of the kiln, on opposite sides of each furnace,or burner, by a-transverse partition, indicated at 20, which does notextend as high as the top of the firing chamber, and preferably has itsupper edge considerably below the top oft-he bridge wall, so that thedischarge passages, 13, merge into a common discharge passage,'13 abovethe tops ofthe transverse partitions, 20.

Means are provided, preferably between adjacent furnaces, forwithdrawing the products of combustion from the firing zone. To thisend, the inner face of the bridge wall is preferably provided adjacentto the level of the lower row, or rows, of goods on the cars, withaplurality of exhaust ports, 14,

preferably, in alignment with the respective transverse partitions, 20,each of said ports being connected by a transverse eduction pipe, orpassage, 15, extending outside of the firing chamber, and connected to aheader,

16, or COllQOtlHg, flue, extending longitudinally of the firing chamber,eachof the educ- Y kiln construction.

tion ports and the p assage'connected therewith, being provided withregulating means. In this instance I have showneach of the eductionpipes,-'.15,- provided withfi a controlling valve,;17,' for illustrativepurposes, but obviously anyxform of. damper or. regulating means, whichwill withstand the high temperature of the products of combustion willbe employed. 'The eduction'pipes, 15, may extend horizontally throughthe kiln wall, or may be'connected many other manner,witl1 thecollecting flue,16, whichmay be located upon or underneath the ground,and below the kiln, if desired. For, greater clearness, have shown thecollecting fine in this instance'located outside of the firing zone, inalignment with the. passages, 15,v and ports,14, but these details ofconstruction may be variedto suit the ideas of different constructorsand the general character of In order 'to secure the withdrawal of theproducts of combustion, means are provided to create a suc'tion,forrarifica-tion in: the collecting pipe, and'the eduction ports orpassages connected therewith. Any suitable device for this'purPOsecan beemployed, In the present instance, I have shown aian or air forcingdevice, indicated at 18, and provided with an injector nozzledischarging into the collecting flue, v16, as indicated in dotted linesat19, but any other form of means for producing suction may be employed.

I The products of combustion discharged into the collecting fine, 16,are very highly heated, and a considerable portion of this heat can beadvantageouslyutilized for heating the drier, or driers, in which theceramic products are dried, preliminary to firing them in the'kiln.These, products of combustion can also be employed for heating air'tosupply thefurnaces, and for other purposes. In the present instance, forexample, I have shown the collecting fine, 16, discharging intorecuperator, 21, of any desired type, provided-with separate airpassages,22, through which air, as from a fan, 23, or other air forcmgdevice, may be caused to pass, and become highly heated, said airpassing out, through a pipe, 24, which maybe connected with the airpipe, 10, which supplies airto the heating burners for'the firingzone,-as' shown in Fig. 1, and this air pipe may-also-be connecteddirectly with the drier and discharge clean, heated air into the same,to assist in the drying of the ceramic products, as indicated in saidfigure. The products'of combustion themselves are preferably conducted,

after leaving the recuperator, by a pipe, .25, to heating pipes,indicated at 26, Within the drier, out of communication therewith, in

-which they giverup a large percentage of their remaining heat, to theair circulating in the drier, aftenwhichthey are passed, by a pipe,27,.=t0 a stack, 28, and discharged tinto the atmosphere. -Obviously,the: draft of the stack is suflicient to-provide'the necessary suctioninthe-collectingfiue, 16, and

eduction passages connected therewith, the injector fan, 18, or otherequivalent means, might be dispensed with.

i The cooling zone, (hot the kiln, is provided with awplurality ofinduction ports, ,29,

through which fresh air from the outside of the kiln isintroduced intothe cooling zone 'at. different points longitudinallythereof, along itsentire length, or a portion of its length; The cooling zine is alsoprovided witha plurality of eduction ports, indicatedat 30, forwithdrawing this air after ithas been highly heatech'by convection andradiation, as't'rom the cooling fired products on thecars in the coolingzone, the saideduction' ports being located at dilierent points longi-'tudinally of the cooling zone throughout-a portion, or all of itslength, and either on the sames'idc as the induction ports, or oppositesides, as preferred. In the present instance, in Fig; 1, I have shownthe induction ports located adjacent toithe discharge end of the kiln,remote from the firing zone, and sup plied by a -'pl'urality of pipes,31, provided .with' regulating. devices, 32, from a header,

33,'connected with ai'an, 34, or other air forcing device. Theeductionports, 30, are shown 1 located adjacent to the firing zone, wherethefired products on the cars are at the highest temperature afterleaving the firing zone said educ'tion ports belngconnected wltheduction pipes, 35, provided with regulating tinuously, I prefer toemploy a suitable form of airforcing device, and in the present instanceI have shownra fan, indicated at 42, located in the transfer pipe, orpassage, 38,

for example. The transfer pipe may be locatedunder ground, or properlyprotected by insulating materlal, to prevent loss of heat. :In thisconstructionavery large pro:

portion of the heat of the fired products can be recovered and used forheating large quantities of airdrawn or discharged into thecoolingzoneand facilitating the cooling of the.

Ware, the said heated air being transferred to and dlstribntedthroughoutthe preheating zone'to effect the preheating, water-smokingandoxidization of the unfired ware. Inintrodilcingthe air into thecooling zone at drznvn at the highest temperature, the-last instrumentsof heat being impartedito it from -ware which has just issued from thefiring zone. The introduction of this heated fresh air into thepreheating zone, provides the necessary oxygen for the oxidization andwater-smoking of the brick, and in order to withdraw from the preheatingzone the' vapors and gases produced in the preheating,

oxidization and water-smoking of the brick, or other products. Ipreferably provide the preheating zone with a plurality of eductioneduction pipes,

vidcd with regulating means,

ports, indicated at 43, arranged at different points longitudinally ofthe preheatlng zone and 'connec ted with an eduction pipe, 44,communicating with a header, 45, which isin turn connected by a pipe,46, with suction producing means, as a stack; 47, or exhaust fan, forpositively withdrawing the air, vapors, and gases from the preheatingzone, and further insuring a continuous supply of clean, hot aircontaining the requisite quantity" of oxygen inthe preheating zone. The

i 44, will preferablybe proas valves, 48, and by regulating these valvesand the air inlet valves, 41, the desired graduated temperature maybemaintained within the preheating zone, longitudinally thereof, so as togradually raise the temperature of the ware from the time it enters thepreheating zone until it passes into the firing zone, so as to obtainthe most effective results without checking or cracking, or otherwiseinjuring the ware. and so that when the ware passes into the enteringend of the firing zone, it will have been broughtto a temperature substantially equal to thatwithin the adjacent portion of the firing zone,so that the subsequent step of firing may be. effected by the furtherand graduated increase in temperature prescribed by the heat curvemaintained in the firing zone.

In Figs. 5 and 6 I have shown. a slightly modified form of my invention,in which it is embodied in a kiln, the firing'zone of which is providedwith a row of furnaces on each side. In these figures, partscorresponding to its members a centrally located firing zone,

those shown in Figs. to 4, inclusive, are given the same referencenumerals wlth 100 added, and where the parts are identical, they willnot be again described. As shown m Fig. 6, the firing zone is providedwith two bridge walls, 106', and two rows of furnaces, 107-, in'thisinstance heated by burners, 108, in the same manner as the single row offurnaces shown in the other figures, and the parts are constructed" andoperate substantially as hereinbefore described, except that in thisinstance the products of combustion charged from'both rows offurnacesinto the top of the goods space, indicated at D, within,

are disthe firing zone, and pass. down through the goods and thence outthrough the eduction ports, 114, in the opposite bridge. walls, andthrough the eduction passages, 115, to the collecting fines, or headers,116', on opposite sides of the firing zone. Obviously, each of theseheaders could beconnected to a superheader in the same-manner as theheader, 16, in Fig. 1, for example, but I prefer to connect the twoheaders, 116, together, by a transverse pipe, 116, and pass the productsof combustion from both rows of furnaces through a single recuperator,121, and thence by pipe, 125, to heating passages, 126, in the drier,and

thence to a stack,'128,-by'apipe, 127. The

through a header,133, and regulated in the pipe, 131, provided withvalves, 132, and the cooling zone is also provided with-eduction pi isin turn connected with the'transfer pipe, or passage, 138, in which maybe located a fan or other suctionmeans, 142, for transferring the heatedair from the cooling zone to a header, 139, connected by regulatedpipes, 140, with the preheating zone at intervals "throughout itslength, under the regulation of suitable regulating valves, 141. Thepreheating zone is also provided with eduction pipes, 144, provided withregulating valves, 148, and connected with a header, 145, which isinturn connected bya pipe, 146, with a stack or other exhausting means,147. It will be understood that the operation of this form of kiln isexactly the sameas that previously described, except that the firingzone is provided with two rows of furnaces instead of one.

What I claim and desire to secureby- Letters Patent is 1. A singletunnel kiln, comprising among provided with a series offurnacesdischargis conductedby- 135, connected to a header, 137, whichthe firing zone is'indicated ing their products of combustion into thefir ing zone, means for'withdrawing the products of combustion directlyfrom the firing zone without permitting appreciable longitudinal flow, apreheating zone extending longitudinally from one end of'the firingzone, a cooling zone extending longitudinally from the other end of thefiring zone, a single. hne of goods conveying means extending mount?through all ofsaid zones, means for supplying air from the outside ofthe kiln to the cooling zone for heating it from the hot fired productstherein, and means for Withdrawing said heated air from the cooling zoneand discharging it into the preheating zone for preheating, oxidizingand water-sinokingthe unfired products therein.

2. A single'tunnel comprising among its members, a centrally locatedfiring zone, provided with a series of furnaces discharging theirproducts of combustion into the firing zone, independent means forcontrolling said furnaces, for maintaining a gradually increasingtemperature from one end of the firing zone to the other, means forwithdrawing the products of combustion directly from the firing zonewithout permitting appreciable longitudinal flow, a preheating zonelocated at one end of the firing zone, a cooling zone located at theother end of the firing zone, a

single line of goods conveying means extending through all of saidzones, means for introducing air into the cooling zone in contact withthe heated, fired products therein, and

means for withdrawing said air heated by the latent heat of said firedproducts and trans- 'ferring it to and introducing it into thepreheating zone for preheating, oxidizing and water-smoking the unfiredproducts during their passage to the firing zone.

3. A single tunnel kiln, comprising among its members, a centrallylocated firing zone, provided with a series of furnaces dischargingtheir products of combustion into the firing zone, means for withdrawingtheprodnets of combustion from the firing zone,'a preheating zoneextending longitudinally from one end of the firing zone, a cooling zoneextending longitudinally from the other end ofthe firing zone, a singleline of goods conveying means extending through all of said zones, meansfor supplying air from the outside of the kiln to the cooling zone forheating it from the hot fired products therein, the preheating zonebeing provided with a plurality of air inlets having independentregulating means, located at different points longitudinally of thepreheating zone, and means for withdrawing the heated air from thecooling zone and distributing it to the said inlet passages to preheat,oxidize and water-smoke the unfired products, whereby said inletpassages may be regulated to efiect the gradual raising of thetemperature of the unfired products as they are moved in a directiontoward the firing zone.

4. A single tunnel kiln, comprising among its members, a'centrallylocated firing zone,

provided with aseries of furnacesdischarging their products ofcombustion into the firing zone, means for withdrawing the products ofcombustion from the firing zone, a preheating zone extendinglongitudinally. from one end of the firing zone, a cooling zoneextending longitudinally from the other end of the firing zone, a singleline of goods conthe preheating zone being provided with a plurality ofair inlets having independent regulating means, located at differentpoints longitudinally of the preheating zone, and means for Withdrawingthe heated air from the cooling zone and distributing it to the saidinlet passages, to preheat, oxidize and water-smoke the unfiredproducts, whereby said inlet passages may be regulated to eifect thegradual raising of the temperature of the unfired products as they aremoved in a direction toward the firing zone.

5. A single tunnel kiln, comprising among its members, a centrallylocated firing zone, provided with a series of furnaces dischargingtheirproducts of combustion into the firing zone, means for withdrawingthe products of combustion from the firing zone, a preheating zoneextending longitudinally from one end of the firing zone, a cooling zoneextending longitudinally from the other end of the firingzone, asingleline of goods conveying means extending through all of said zones, meansfor supp.lyingair from the outside of the kiln to the cooling zone forheating it from the hot fired products therein, means for withdrawingthe heated air from the cooling zone and transferring it to anddistributing it into the preheating'zone to preheat, oxidize andwater-smoke the unfired products therein, said preheating zone beingprovided with a plurality of eduction passages and means connectedtherewith for withdrawing air laden with the vapors and gases producedby oxidation and watersmoking from the preheating zone.

6. A single tunnel kiln, comprising among its members, a centrallylocated firing zone, provided with a series of furnaces dischargingtheir products of combustion into the firing zone, means-for withdrawingthe prodnets of combustion from the firing zone, a preheating zoneextending longitudinally from one end of the firing zone, a cooling zoneextending longitudinally from the other 7 7 end of the firing zone, asingle line of goods conveying means extendingthrough all of said zones,means for supplying air from the outside of the kiln to the cooling zonefor heating it from the hot fired products therein, said means beinglocated at different point-s longitudinally of the cooling zone,eduction passages communicating with the cooling zone and located atdifferent points longitudinally thereof, means connected with saideduction ports for withdrawing the heated air from the cooling zone andtransferring it to the preheating zone, and means for discharging saidheated air into the preheating zone at different points longitudinallythereof.

T 7 A single tunnel kiln, comprising among its members, a centrallylocated firing zone, provided with a series of furnaces dischargingtheir products of combustion into the firing zone, means for withdrawingthe products of combustion from the firing zone, a preheating zoneextending longitudinally from one end of the firing zone, a cooling zoneextending longitudinally from the other end of the firing zone, a singleline of goods conveying means extending through all of said zones, meansfor supplying air from the outside of the kiln to the cooling zone forheating it from the hot fired products therein, said means being locatedat different points longitudinally of the cooling zone, eductionpassages communicating with the cooling zone and located at differentpoints longitudinally thereof, means connected with said eduction portsfor Withdrawing the heated air from the" cooling zone and transferringit to the preheating zone, means for discharging said heat ed air intothe preheating-zone different points longitudinally thereof, the airinlet passages and eduction passages of the cooling zone being providedwith independent regu 'lating means, and independent regulating meansfor controlling the admission of said heated air at said differentpoints longitudinally of the preheating zone to establish and maintaingradually increasing temperatures therein from the, entering end of thepreheating zone, in a direction to ward the firing zone.

8. A single tunnel kiln, comprising among its members, a centrallylocated firing zone, provided'with a series of furnaces dischargingtheir products of combustion into the firing zone, means for Withdrawingthe products of combustion from the firing zone, a preheating zoneextending longitudinally from one end of the firing zone, a cooling zoneextending longitudinally from the other end of the firing zone, a.single line of goods conveying means extending through all of saidzones, means for supplying air from the outside of the kiln to thecooling zone for heating it from the hot fired products therein, saidmeans being located at different points longitudinally of the coolingzone, eduction passages communicating with the cooling zone and locatedat different points longitudinally thereof, means connected with saideduction ports for withdrawing the heated air from the cooling zone andtransferring it to the preheating zone,

.means for, discharging said heated air into the prehet ting zone atdifferent points longitudinally thereof, the air inlets for the coolingzone being located adjacent to the delivery end thereof, and theeduction passages of the cooling zone being located adjacent to thefiring zone whereby the air is caused to travel lengthwise of thecooling zone and to become gradually heated, and is withdrawn from thefiring zone, means for withdrawing the prodnets of combustion from thefiring zone, a preheating zone extending longitudinally from one end ofthe firing zone, a cooling zone extending longitudinally from the otherend of the firing zone, a single line of goods conveying means extendingthrough all of said zones, means for supplying air from the outside ofthe kiln to the cooling zone for heating it fromthe hot fired productstherein, said means being located at different points longitudinally ofthe cooling zone, eduction passages communicating with the cooling zoneand located at different points longitudinally thereof, means connectedwith said eduction ports for Withdrawing the heat-ed air from thecooling zone and transferring it to the preheating zone, means fordischarging said heated air into the preheating zone atdifferent pointslongitudinally thereof,-independent regulating devices for controllingthe inlet of said heated air at. said points, eduction passagesconnected with said preheating zone and located at different pointslongitudinally thereof, independent regulating means therefor, and meansconnected with said eduction passages for withdrawing the heated airadmitted thereto laden with vapors and gases produced by the heating,oxidation and water-smoking of the ware.

10. A single tunnel kiln, comprising among its members a centrallylocated firing zone, provided with a series of furnaces disa chargingtheir products of combustion into the firing zone, means for Withdrawingthe products of combustion directly from the firing zone withoutpermitting appreciable longitudinal flow, a preheating zone extend-' inglongitudinally from one end of the firing zone, a cooling zone extendinglongitudinally from the other end of the firing zone, a single line ofgoods conveying means extending through all of said zones, means forsupplying air from the outside of the kiln to the coolin zone adjacentto the discharge end thereof For heating said air from the hot firedproducts therein, and means for withdrawing said heated air from thecooling zone adjacent to the end thereof nearest the firing zone, andtransferring said air so withdrawn to and discharging it into thepreheating zone for preheating, oxidizing and water-smoking the unfiredproducts therein. 11. A single tunnel kiln, comprising among its membersa centrally located firing zone, provided with a series of furnacesdischarging their products of combustioninto the firing zone, means forwithdrawing the products of combustion from the firing zone,

a preheating zone extending longitudinally from one end of the firingzone, a cooling zone extending longitudinally from the other end of thefiring zone, a single line of goods conveying means extending throughall of said zones, said cooling zone being provided With a plurality ofair inlets adjacent to the discharge end of said zone and arranged atdifferent points longitudinally thereof, said cooling zone being alsoprovided With eduction apertures atseparated points longitudinallythereof and located adjacent to the end of the cooling zone nearest thefiring zone, and means for Withdrawing the heated air from the coolingzone through said eduction apertures at the points of highest heat insaid zone, anddischarging said highly heated air into the preheatingzone adjacent to the end thereof nearest the firing zone, and at otherseparated points longitudinally thereof for preheating, oxidizing andWater-smoking the unfired products therein.

In testimony whereof I aflix my signature.

WILLIAM LEE HANLEY, JR.

